Gravity What is Gravity?

Sir Isaac Newton (1642-1727) Used generations worth of observations made of the stars and planets in the night sky to establish the Law of Gravity.

Gravity is an attractive force between any 2 objects

The force of that attraction depends on 2 things: Mass of each object The distance between them

GRAVITATIONAL FORCE INCREASES as the MASS of either object INCREASES FORCE also INCREASES as the objects MOVE CLOSER.

pulls on every other object Every object in the universe pulls on every other object in the universe.

WHAT? I don’t feel anything. Why is that?

Gravity is one of 4 basic forces: Gravity Electrical Magnetic Nuclear

Law of Universal Gravitation Newton’s law of gravitation can be expressed by this equation: Force of gravity = constant x (mass of obj 1 x mass of obj 2) / (distance between objects)² OR F = G (m1 x m2) / d²

F = G (m1 x m2) / d² In this formula: G = a constant called the universal gravitational constant d = the distance between 2 masses m1 = the mass of the 1st object m2 = the mass of the 2nd object

Allows you to calculate the force of gravity between 2 objects if you know: The mass of each object The distance between them

Range of Gravity Gravitational force between 2 objects decreases very quickly the further apart the 2 objects become.

More distance = Less Gravitational Force

Gravitational force will NEVER equal zero

What is the acceleration of gravity? (how fast is an object pulled towards Earth) 9.8 m/s² Given the symbol g

Here’s the equation to find the force of Earth’s gravity Force (N) = mass (kg) x acceleration (m/s²) OR F = mg

Weight can be calculated with the same equation: The gravitational force exerted on an object is called the objects weight. Weight can be calculated with the same equation: Weight (N) = mass (kg) x accel of gravity (m/s²) W= mg

Mass is a measure of the amount of matter in an object Weight is a force Mass and weight are related because weight increases as mass increases.

Projectile motion Why do quarterbacks, dart player and archers all aim above their targets?

Earth’s gravity causes projectiles to follow a curved path. Anything that is thrown or shot through the air is called a projectile. Earth’s gravity causes projectiles to follow a curved path.

Horizontal and vertical motions When you throw a ball, the force exerted by your hand gives the ball a forward motion, or horizontal motion. Once you let go of the ball, gravity is pulling it downward giving it vertical motion.

Centripetal force The force that keeps objects moving in a curved direction. Think of a car going around a curve. Think of the swing rides at Carowinds. These objects are kept from moving in a straight line because of the force accelerating it towards the center.

Gravity as a centripetal force? Earth’s gravity exerts a centripetal force on the Moon that keeps it moving in a nearly circular orbit.